package com.bolins.util;

import java.awt.image.BufferedImage;   
import java.io.File;   
import javax.imageio.ImageIO;   
  

/**
 * Java 高品质缩略图
 * @author thinkpad
 *
 */
public class ScaleImage {   
  
    private int width;   
  
    private int height;   
  
    private int scaleWidth;   
  
    double support = (double) 3.0;   
  
    double PI = (double) 3.14159265358978;   
  
    double[] contrib;   
  
    double[] normContrib;   
  
    double[] tmpContrib;   
  
    int startContrib, stopContrib;   
  
    int nDots;   
  
    int nHalfDots;   
  
    /**   
     * Start: Use Lanczos filter to replace the original algorithm for image  
     * scaling. Lanczos improves quality of the scaled image modify by :blade  
     */    
    public static void main(String[] args) {   
        ScaleImage is = new ScaleImage();   
        try {   
            is.saveImageAsJpg("d:/3.jpg", "d:/3-s.jpg", 300,   
                    300);   
            System.out.println("success");   
        } catch (Exception e) {   
            e.printStackTrace();   
        }   
    }   
      
    /**  
     *   
     * @param fromFileStr 原图片地址  
     * @param saveToFileStr  生成缩略图地址  
     * @param formatWideth  生成图片宽度  
     * @param formatHeight  formatHeight高度  
     */  
    public void saveImageAsJpg(String fromFileStr, String saveToFileStr,   
            int formatWideth, int formatHeight) throws Exception {   
        BufferedImage srcImage;   
        File saveFile = new File(saveToFileStr);   
        File fromFile = new File(fromFileStr);   
        srcImage = javax.imageio.ImageIO.read(fromFile); // construct image   
        int imageWideth = srcImage.getWidth(null);   
        int imageHeight = srcImage.getHeight(null);   
        int changeToWideth = 0;   
        int changeToHeight = 0;   
        if (imageWideth > 0 && imageHeight > 0) {   
            // flag=true;   
            if (imageWideth / imageHeight >= formatWideth / formatHeight) {   
                if (imageWideth > formatWideth) {   
                    changeToWideth = formatWideth;   
                    changeToHeight = (imageHeight * formatWideth) / imageWideth;   
                } else {   
                    changeToWideth = imageWideth;   
                    changeToHeight = imageHeight;   
                }   
            } else {   
                if (imageHeight > formatHeight) {   
                    changeToHeight = formatHeight;   
                    changeToWideth = (imageWideth * formatHeight) / imageHeight;   
                } else {   
                    changeToWideth = imageWideth;   
                    changeToHeight = imageHeight;   
                }   
            }   
        }   
  
        srcImage = imageZoomOut(srcImage, changeToWideth, changeToHeight);   
        ImageIO.write(srcImage, "JPEG", saveFile);   
    }   
  
    public BufferedImage imageZoomOut(BufferedImage srcBufferImage, int w, int h) {   
        width = srcBufferImage.getWidth();   
        height = srcBufferImage.getHeight();   
        scaleWidth = w;   
  
        if (DetermineResultSize(w, h) == 1) {   
            return srcBufferImage;   
        }   
        CalContrib();   
        BufferedImage pbOut = HorizontalFiltering(srcBufferImage, w);   
        BufferedImage pbFinalOut = VerticalFiltering(pbOut, h);   
        return pbFinalOut;   
    }   
  
    /**   
     * 决定图像尺寸  
     */  
    private int DetermineResultSize(int w, int h) {   
        double scaleH, scaleV;   
        scaleH = (double) w / (double) width;   
        scaleV = (double) h / (double) height;   
        // 需要判断一下scaleH，scaleV，不做放大操作   
        if (scaleH >= 1.0 && scaleV >= 1.0) {   
            return 1;   
        }   
        return 0;   
  
    } // end of DetermineResultSize()   
  
    private double Lanczos(int i, int inWidth, int outWidth, double Support) {   
        double x;   
  
        x = (double) i * (double) outWidth / (double) inWidth;   
  
        return Math.sin(x * PI) / (x * PI) * Math.sin(x * PI / Support)   
                / (x * PI / Support);   
  
    }   
  
    private void CalContrib() {   
        nHalfDots = (int) ((double) width * support / (double) scaleWidth);   
        nDots = nHalfDots * 2 + 1;   
        try {   
            contrib = new double[nDots];   
            normContrib = new double[nDots];   
            tmpContrib = new double[nDots];   
        } catch (Exception e) {   
            System.out.println("init   contrib,normContrib,tmpContrib" + e);   
        }   
  
        int center = nHalfDots;   
        contrib[center] = 1.0;   
  
        double weight = 0.0;   
        int i = 0;   
        for (i = 1; i <= center; i++) {   
            contrib[center + i] = Lanczos(i, width, scaleWidth, support);   
            weight += contrib[center + i];   
        }   
  
        for (i = center - 1; i >= 0; i--) {   
            contrib[i] = contrib[center * 2 - i];   
        }   
  
        weight = weight * 2 + 1.0;   
  
        for (i = 0; i <= center; i++) {   
            normContrib[i] = contrib[i] / weight;   
        }   
  
        for (i = center + 1; i < nDots; i++) {   
            normContrib[i] = normContrib[center * 2 - i];   
        }   
    } // end of CalContrib()   
  
    // 处理边缘   
    private void CalTempContrib(int start, int stop) {   
        double weight = 0;   
  
        int i = 0;   
        for (i = start; i <= stop; i++) {   
            weight += contrib[i];   
        }   
  
        for (i = start; i <= stop; i++) {   
            tmpContrib[i] = contrib[i] / weight;   
        }   
  
    } // end of CalTempContrib()   
  
    private int GetRedValue(int rgbValue) {   
        int temp = rgbValue & 0x00ff0000;   
        return temp >> 16;   
    }   
  
    private int GetGreenValue(int rgbValue) {   
        int temp = rgbValue & 0x0000ff00;   
        return temp >> 8;   
    }   
  
    private int GetBlueValue(int rgbValue) {   
        return rgbValue & 0x000000ff;   
    }   
  
    private int ComRGB(int redValue, int greenValue, int blueValue) {   
  
        return (redValue << 16) + (greenValue << 8) + blueValue;   
    }   
  
    // 行水平滤波   
    private int HorizontalFilter(BufferedImage bufImg, int startX, int stopX,   
            int start, int stop, int y, double[] pContrib) {   
        double valueRed = 0.0;   
        double valueGreen = 0.0;   
        double valueBlue = 0.0;   
        int valueRGB = 0;   
        int i, j;   
  
        for (i = startX, j = start; i <= stopX; i++, j++) {   
            valueRGB = bufImg.getRGB(i, y);   
  
            valueRed += GetRedValue(valueRGB) * pContrib[j];   
            valueGreen += GetGreenValue(valueRGB) * pContrib[j];   
            valueBlue += GetBlueValue(valueRGB) * pContrib[j];   
        }   
  
        valueRGB = ComRGB(Clip((int) valueRed), Clip((int) valueGreen),   
                Clip((int) valueBlue));   
        return valueRGB;   
  
    } // end of HorizontalFilter()   
  
    // 图片水平滤波   
    private BufferedImage HorizontalFiltering(BufferedImage bufImage, int iOutW) {   
        int dwInW = bufImage.getWidth();   
        int dwInH = bufImage.getHeight();   
        int value = 0;   
        BufferedImage pbOut = new BufferedImage(iOutW, dwInH,   
                BufferedImage.TYPE_INT_RGB);   
  
        for (int x = 0; x < iOutW; x++) {   
  
            int startX;   
            int start;   
            int X = (int) (((double) x) * ((double) dwInW) / ((double) iOutW) + 0.5);   
            int y = 0;   
  
            startX = X - nHalfDots;   
            if (startX < 0) {   
                startX = 0;   
                start = nHalfDots - X;   
            } else {   
                start = 0;   
            }   
  
            int stop;   
            int stopX = X + nHalfDots;   
            if (stopX > (dwInW - 1)) {   
                stopX = dwInW - 1;   
                stop = nHalfDots + (dwInW - 1 - X);   
            } else {   
                stop = nHalfDots * 2;   
            }   
  
            if (start > 0 || stop < nDots - 1) {   
                CalTempContrib(start, stop);   
                for (y = 0; y < dwInH; y++) {   
                    value = HorizontalFilter(bufImage, startX, stopX, start,   
                            stop, y, tmpContrib);   
                    pbOut.setRGB(x, y, value);   
                }   
            } else {   
                for (y = 0; y < dwInH; y++) {   
                    value = HorizontalFilter(bufImage, startX, stopX, start,   
                            stop, y, normContrib);   
                    pbOut.setRGB(x, y, value);   
                }   
            }   
        }   
  
        return pbOut;   
  
    } // end of HorizontalFiltering()   
  
    private int VerticalFilter(BufferedImage pbInImage, int startY, int stopY,   
            int start, int stop, int x, double[] pContrib) {   
        double valueRed = 0.0;   
        double valueGreen = 0.0;   
        double valueBlue = 0.0;   
        int valueRGB = 0;   
        int i, j;   
  
        for (i = startY, j = start; i <= stopY; i++, j++) {   
            valueRGB = pbInImage.getRGB(x, i);   
  
            valueRed += GetRedValue(valueRGB) * pContrib[j];   
            valueGreen += GetGreenValue(valueRGB) * pContrib[j];   
            valueBlue += GetBlueValue(valueRGB) * pContrib[j];   
            // System.out.println(valueRed+"->"+Clip((int)valueRed)+"<-");   
            //   
            // System.out.println(valueGreen+"->"+Clip((int)valueGreen)+"<-");   
            // System.out.println(valueBlue+"->"+Clip((int)valueBlue)+"<-"+"-->");   
        }   
  
        valueRGB = ComRGB(Clip((int) valueRed), Clip((int) valueGreen),   
                Clip((int) valueBlue));   
        // System.out.println(valueRGB);   
        return valueRGB;   
  
    } // end of VerticalFilter()   
  
    private BufferedImage VerticalFiltering(BufferedImage pbImage, int iOutH) {   
        int iW = pbImage.getWidth();   
        int iH = pbImage.getHeight();   
        int value = 0;   
        BufferedImage pbOut = new BufferedImage(iW, iOutH,   
                BufferedImage.TYPE_INT_RGB);   
  
        for (int y = 0; y < iOutH; y++) {   
  
            int startY;   
            int start;   
            int Y = (int) (((double) y) * ((double) iH) / ((double) iOutH) + 0.5);   
  
            startY = Y - nHalfDots;   
            if (startY < 0) {   
                startY = 0;   
                start = nHalfDots - Y;   
            } else {   
                start = 0;   
            }   
  
            int stop;   
            int stopY = Y + nHalfDots;   
            if (stopY > (int) (iH - 1)) {   
                stopY = iH - 1;   
                stop = nHalfDots + (iH - 1 - Y);   
            } else {   
                stop = nHalfDots * 2;   
            }   
  
            if (start > 0 || stop < nDots - 1) {   
                CalTempContrib(start, stop);   
                for (int x = 0; x < iW; x++) {   
                    value = VerticalFilter(pbImage, startY, stopY, start, stop,   
                            x, tmpContrib);   
                    pbOut.setRGB(x, y, value);   
                }   
            } else {   
                for (int x = 0; x < iW; x++) {   
                    value = VerticalFilter(pbImage, startY, stopY, start, stop,   
                            x, normContrib);   
                    pbOut.setRGB(x, y, value);   
                }   
            }   
  
        }   
  
        return pbOut;   
  
    } // end of VerticalFiltering()   
  
    int Clip(int x) {   
        if (x < 0)   
            return 0;   
        if (x > 255)   
            return 255;   
        return x;   
    }   
}  